I used landscape foam. You can use a plastic bag to hold the foam in place until it hardens. Plastic does not stick to hard when it is dry. it's called Touch n Foam.
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regards,
Extremebike
2004 Ford F550 6l Lariat SuperCrew, Fontaine Bed,
Link Systems Air Ride
2011 Sterling 32RL with Michelin XPS tires
I used expanding foam mixed with steel wool. I also use an ultrasonic repeller and numerous glue traps in the basement area. Don't want any varmints messing with all of the wiring and hydraulics. No signs so far.
Good luck,
Don
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Don and Michele
3 Adult Children - 5 Grandchildren
Present campsite - future homesite